Means for treating bank gravel



Feb. 5, 1957 H. HARRIS 2,780,417

-MEANS FOR TREATING BANK GRAVEL Filed April 1, 1954 2 Sheets-Sheet 1 INVN TOR.

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Feb. 5, 1957 H. HARRIS 2,780,417

MEANS FOR TREATING BANK GRAVEL Filed April 1, 1954 2 Sheets-Sheet 2 IN V EN TOR.

United States Patent "ice A MEANS FOR TREATING BANK GRAVEL Holbert L. Harris, Arlington County, Va.

Application April 1, 1954, Serial No. 420,253, 2 Claims. (Cl. 241-152 This invention relates to a machine for treating bank gravel of the kind used in road building or in the making of concrete aggregate and it has for its object to so treat such gravel as to leave a final product which will, with certainty, meet the tests and requirements prescribed by the highway departments of the various states, counties and cities.

In most cases the gravel masses as theyare taken from the banks or pits are composed of gravel, clay and sand. It is customary to first wash the gravel free of the adhering clay and sand. However, not all of the remaining gravel is acceptable to highway departments but upon the contrary it must pass certain tests before it will be accepted. One test is that of hardness and freedom from friability and in this test, which is known as the California rattler test, a sample from a bulk mass of the washed gravel, offered for use, is placed in a revolving drum together with some steel balls. If after a determined period of rotation of the drum, at a certain speed, more than a certain percentage of the sample has been broken to such size that it will pass through a screen of a prescribed mesh the whole mass from which the sample was taken, is rejected.

Broadly stated all of the gravel which comes from the Washers, consisting of hard gravel, soft gravel and gravel of intermediate degrees of hardness,'passes through my machine in which the gravel is hurled forcibly by centrifugal force against one or more very hard and unyielding abutments. The result is that the portions which are so soft, brittle or friable as to be reduced below a certain size, are so reduced, and they are later removed from the mass. Thus I am able to offer for sale the residual product with the certainty that under test no more than the permissible quantity of low grade material will be found in the mass.

In the accompanying drawings:

Fig. 1 is a vertical sectional view through one type of machine embodying the invention;

Fig. 2 is a plan view of a drum which carries the upper spider, hereinafter described;

Fig. 3 is a plan view of one of the centrifugal discs, and

Fig. 4 is a horizontal sectional view upon line 44 of Fig. 1.

Like numerals designate corresponding parts in all of the figures of the drawings.

The machine of my invention comprises a base casing section 5, which carries a ring 6, said ring being supported by spider legs 7 from the section 5. A thick and heavy metal band 8 supports a top 9 and hopper 10, through which hopper the material is fed into the machine. Located interiorly within band 8 and carried thereby is a ring 11 of an exceedingly hard metal. Band 8 and hard ring 11 complementally bear upon the upper edge of a cylinder or drum 12 and the lower edge of this drum over-laps and complementally bears upon a second band 13. Band 13 carries a second hard metal ring 14 and band 13 and ring 14 complementally overlap and have a bearing upon the upper edge of the base section 5. The

2,780,417 Patented Feb. 5, 1957 several parts named are forcibly drawn together and into firmly united position, by tie rods 15 and nuts 16. Suitable ears 17 are formed upon the members 5 and 8 for the tie rods.

The drum 12 is spanned by a spider 18 which carries a bearing boss 18a at its center. A plate 19 bolted at 20 to the under face of spider 18, supports a thrust bearing 21. Bearing 21 together with a second thrust bearing 22 located on top of ring 6 provide a mounting for a vertical shaft 23. A dust cap 24 is disposed to cover bearing 22. A bevel gear wheel 25 on the lower end of shaft 23 meshes with a second bevel gear or pinion 26 that is carried by a drive shaft 27. The gears 25 and 26 are located in protected position within ring 6. Drive shaft 27 projects through a sleeve 28 to the exterior of easing section 5 where power from any suitable source may be imparted to it.

Vertical shaft 23 carries centrifugal discs 29 and 30, having ribs or blades 29a and 30a upon them and disposed at such levels that gravel hurled therefrom by centrifugal force will be forcibly impacted against the hard metal rings 11 and 14 respectively. The material veyor belt 33 by which it is conveyed to conventional screening devices where the content which has been reduced beyond the desired size by the impacting of the whole mass forcibly against the hard metal rings, may be separated from the remainder of the mass. Such remainder may then be offered for use with the certainty that it will pass the test to be imposed thereon. The material discarded may be used as sand in the manufacture of concrete aggregate.

The machine described enables me to effect large economies in the quarrying and marketing of bank gravel in that it avoids the possibility that large quantities of gravel may be hauled to the job and then rejected. Further it avoids the necessity of delivering a higher quality of gravel than necessity requires because it renders possible the prior determination of the character of the material to be sold before it is offered for sale. While I have shown two of the centrifugal discs to yield two stages of treatment of the gravel it will be understood that these may be increased in number if desired. There is a distinct advantage in subjecting the material to more than one stage of treatment, because the speed of rotation of the discs may be so adjusted that the equivalent of a plurality of moderate blows may be given the particles of gravel rather than a single more severe blow. Even fairly hard gravel particles might be broken if subjected to too severe a blow. The successive more moderate blows make it possible to more accurately adjust the output of the machine.

While I prefer to use a plurality of stages of treatment of the material the basic thought of impacting the whole mass against a hard surface would be applicable to a single stage of treatment.

It is clear that other forms of machines might be devised to carry out the inventive idea disclosed. Therefore it is to be understood that the invention is not limited to the particular machine shown but that it includes within its purview whatever changes fairly fall within either the terms or the spirit of the appended claims.

I claim:

1. A machine of the character described comprising a circular base member, spider arms carried thereby, an open ring supported centrally in the base member by said spider arms, a bearing supported by said ring, a thick metal band carrying an intern-a1 hard metal ring, said hard metal ring and band complementally bearing upon the upper edge of the base member, a cylinder the lower edge of which bears complementally upon the said band and hard metal ring, spider arms spanning said cylinder having a centrally arranged bearing supporting portion, abearing carried thereby, a vertical shaft rnounted in said bearings, a pair of meshing bevel gear wheels disposed in the said open ringof the base member, one of which gears is fast onthe vertical shaft, and a driven shaft projecting into said ring from exterior of the base member and upon which the other gear wheel is fast, a plurality of centrifugal disks fixed upon said shaft, an upper band and hard metal ring complementally bearing upon the upper edge of said cylinder, saidhard metalrings lying in position to constitute abutments to receive gravel hurled from the centrifugal disks, means for drawing the last named band and base member forcibly toward each. ether. to bind the several portions together, means for feeding material upon the uppermost disk, and means for conducting material discharged from the uppermost disk to the disk therebelow.

2. A machine of the character described comprising a cylindrical base member, a cylinder of substantially the same internal diameter as the base member and elevated thereabove, a thick metal band and a hard metal ring within the band, said band and hard metal ring being disposed between the upper edge of the base member and the lower edge of the said cylinder, with the said edges of the base member and cylinder overlapping and bearing complementally upon both the band and ring, means References Cited in the file of this patent UNITED STATES PATENTS 87,716 Smith Mar. 9, 1869 139,782 Goodhart June 10, 1873 160,618 Rudy Mar. 9, 1875 569,238 Sauerbrey Oct. 13, 1896 1,147,211 Coleman et a1 July 20, 1915 1,458,387 Bourne June 12, 1923 1,636,033 Agnew July 19, 1927 1,645,847 Anthony Oct. 18, 1927 1,656,756 Payne Ian. 17, 1928 1,713,297 Olslon May 14, 1929 1,758,010 Pettinos May 13, 1930 1,921,914 Edman Aug. 8, 1933 1,997,031 Allswede Apr. 9, 1935 2,128,848 Rafetto Aug. 30, 1938 2,144,384 Mikau Jan. 17, 1939 2,306,427 Christman et a1. Dec. 29, 1942 FOREIGN PATENTS 5,246 Great Britain of 1881 654,002 France Nov. 20, 1928 

